A breath of fresh air!

During LS1 the teams in charge of the cooling and ventilation systems of the CERN accelerators will perform maintenance work on all the equipment for which they are responsible. What with replacing complete systems, making improvements or bringing equipment back up to scratch, their workload looks like being a heavy one over the coming months.


Installing a fan in a cooling tower at Point 6 of the LHC in 2009. A similar exercise will be carried out in a few weeks.

CERN's Cooling and Ventilation (CV) Group is responsible for the operation and maintenance of the cooling systems, pumping stations, air-conditioning facilities and fluid distribution systems for CERN's Computer Centre, the PS, the SPS, the LHC and their respective experiment areas. All these systems are equally indispensable and their maintenance is far from being a straightforward operation. During operating periods, the technical stops are too short for any major maintenance work. Although the work takes only a few days, such operations have an impact of several weeks on the schedules of all the downstream installations and especially on the cryogenics.

This is why LS1, which is a period of intense activity for all CERN teams working on the accelerators, is also a crucial time for the CV Group. “During this long technical shutdown we have to bring all the equipment, on which no maintenance interventions have been possible for three years, back up to scratch and prepare it for three further years of non-stop operation,” underlines deputy CV group leader Serge Deleval who is in charge of the work. “To achieve this gargantuan task, our teams have been reinforced: some 60 contractors, under the watchful eye of 15 CERN staff members, will be performing operations in parallel until the machines start up once again.” In addition, some of the equipment will be consolidated to allow more regular maintenance. At Points 4, 6 and 8 of the LHC, for instance, the CV Group has installed new cooling towers to take over from the main cooling towers when the latter are being maintained. It is worth remembering that, in parallel to this maintenance work, many systems for which the CV Group are responsible will continue to function just as they do in a period of operation with beam. This is for safety reasons and to allow other groups to test and install their equipment during LS1.

Most of the cooling and ventilation equipment dates back to the commissioning of the accelerators and many items are beginning to show their age. The PS ventilation systems, for instance, date back to 1957 and will be completely replaced to guarantee operational reliability and to meet new safety standards. “Once current operations to eliminate asbestos from the PS tunnel and galleries have been completed, an entirely new ventilation system will be installed with a much more efficient capacity for smoke removal and, above all, for ventilation of the radioactive areas,” adds Serge Deleval. On the Meyrin site, the demineralised water production plant for all the CERN sites will be substantially upgraded and the oldest part dismantled to increase the plant’s reliability.

The underground water pumping system will also be replaced at Point 3 of the LHC. “This area is particularly critical for the LHC infrastructure since it intersects with an underground river,” explains Serge Deleval. “The river water pumps have to operate continuously, otherwise the tunnel would rapidly flood.” The new more powerful pumps, of a type that is used in mines, will be able to remove sediments carried by the river water as well as the water itself. This will avoid the CV Group periodically having to clean the pumping area of sediments, entailing the shutdown of the LHC, as is currently the case.

by Anaïs Schaeffer